Cannabis use was linked to less depression and suicidal ideation in people with PTSD
In a nationally representative Canadian survey, cannabis use appeared to weaken the association between PTSD and both severe depression and suicidal ideation.
Quick Facts
What This Study Found
Among 24,089 respondents in the Canadian Community Health Survey, people with PTSD who used cannabis had lower odds of experiencing a major depressive episode and suicidal ideation compared to those with PTSD who did not use cannabis, after controlling for demographics and comorbidities.
Key Numbers
24,089 respondents; 420 (1.7%) had PTSD; 28.2% of those with PTSD used cannabis vs. 11.2% without PTSD; cannabis use associated with reduced odds of depression and suicidal ideation in PTSD group.
How They Did This
Cross-sectional analysis of the 2012 Canadian Community Health Survey-Mental Health (n=24,089) using logistic regression with interaction terms for cannabis and PTSD status.
Why This Research Matters
PTSD dramatically increases the risk of depression and suicide. If cannabis genuinely moderates this relationship, it could have significant implications for treatment, though observational data alone cannot prove causation.
The Bigger Picture
This population-level finding aligns with growing clinical interest in cannabinoids for PTSD treatment. However, the cross-sectional design means self-medication cannot be distinguished from therapeutic benefit.
What This Study Doesn't Tell Us
Cross-sectional design cannot establish causation; self-reported data; cannabis use patterns (frequency, type) were not detailed; potential for residual confounding; PTSD sample relatively small.
Questions This Raises
- ?Would longitudinal data confirm a protective effect?
- ?Which cannabis types or patterns of use might explain this association?
Trust & Context
- Key Stat:
- Cannabis use weakened the PTSD-depression and PTSD-suicidal ideation link
- Evidence Grade:
- Moderate: large nationally representative sample with appropriate statistical controls, but cross-sectional design limits causal inference.
- Study Age:
- Published 2020.
- Original Title:
- Does cannabis use modify the effect of post-traumatic stress disorder on severe depression and suicidal ideation? Evidence from a population-based cross-sectional study of Canadians.
- Published In:
- Journal of psychopharmacology (Oxford, England), 34(2), 181-188 (2020)
- Authors:
- Lake, Stephanie(16), Kerr, Thomas(11), Buxton, Jane(4), Walsh, Zach, Marshall, Brandon Dl, Wood, Evan, Milloy, M-J
- Database ID:
- RTHC-02667
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Did cannabis reduce PTSD symptoms directly?
The study did not measure PTSD symptom severity directly. It found that cannabis use weakened the statistical association between having PTSD and experiencing depression or suicidal ideation.
Does this prove cannabis treats PTSD-related depression?
No. The cross-sectional design cannot establish causation. People with PTSD who use cannabis may differ in other ways that explain the association.
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Cite This Study
https://rethinkthc.com/research/RTHC-02667APA
Lake, Stephanie; Kerr, Thomas; Buxton, Jane; Walsh, Zach; Marshall, Brandon Dl; Wood, Evan; Milloy, M-J. (2020). Does cannabis use modify the effect of post-traumatic stress disorder on severe depression and suicidal ideation? Evidence from a population-based cross-sectional study of Canadians.. Journal of psychopharmacology (Oxford, England), 34(2), 181-188. https://doi.org/10.1177/0269881119882806
MLA
Lake, Stephanie, et al. "Does cannabis use modify the effect of post-traumatic stress disorder on severe depression and suicidal ideation? Evidence from a population-based cross-sectional study of Canadians.." Journal of psychopharmacology (Oxford, 2020. https://doi.org/10.1177/0269881119882806
RethinkTHC
RethinkTHC Research Database. "Does cannabis use modify the effect of post-traumatic stress..." RTHC-02667. Retrieved from https://rethinkthc.com/research/lake-2020-does-cannabis-use-modify
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.